1. Field of the Invention
The present invention relates to a chemical supply pump, a chemical supply apparatus, and a chemical supply system (a chemical supply method) for accurately supplying a desired quantity of a liquid chemical, in particular, it is suitable for applying to a substrate cleaning apparatus (a substrate cleaning method) for cleaning semiconductor wafers or the like.
2. Description of the Related Art
Conventionally in a semiconductor wet process, used is a substrate cleaning apparatus for performing a process such as cleaning with a cleaning liquid of ultrapure water and a liquid chemical. As such a substrate cleaning apparatus, remarked is a substrate single wafer spin cleaning apparatus in which substrates are loaded one by one and a cleaning liquid is supplied with rotating the substrate in a circumferential direction.
In a conventional substrate cleaning apparatus, it was indispensable to provide a plurality of large-sized cleaning liquid storage tanks for preparing various liquid chemicals at desired concentrations necessary for cleaning. Accordingly, the whole system becomes a very large scale and complex inevitably in this case.
Besides, due to the necessity of providing a plurality of cleaning liquid storage tanks according to the necessary kinds of cleaning liquids as described above, particles are easy to mix in when a cleaning liquid is compounded. Further, generation of particles and (metal) contamination from various liquid-contact portion caused by complication of the substrate cleaning apparatus is in question.
In this manner, at present, it is difficult to avoid increases in scale and complication of the whole apparatus attendant upon an increase in cleaning speed of substrate cleaning apparatus. It is the present state that establishment of a technique of preventing particle-mixing or the like in a cleaning liquid, is eagerly desired.